    array_of_hashes.any? {|h| h[:a] == 11}

You did ask for a boolean result in the OQ, but if you really want the hash element itself do:

    array_of_hashes.detect {  |h| h[:a] == 11 }

If you want the result really fast you could group the original object and then get the result with a single hash lookup:

    t = array_of_hashes.group_by { |x| x[:a] }
    t[11]


I wat to do something like this:

    if (viewController.mapView) [viewController.mapView someMethod];

However, if mapView is not a class variable, this crashes. How do I check if mapView exists?

In Objective C, can you check if an object has a particular property or message?

So here&#39;s an interesting situation when using git and python, and I&#39;m sure it happens for other situations as well.

Let&#39;s say I make a git repo with a folder /foo/. In that folder I put /foo/program.py. I run program.py and program.pyc is created. I have *.pyc in the .gitignore file, so git doesn&#39;t track it. 

Now let&#39;s say I make another branch, dev. In this dev branch, I remove the /foo/ folder entirely.

Now I switch back to the master branch, and /foo/ reappears. I run the program.py and the program.pyc file reappears. All is well.

I switch back to my dev branch. The /foo/ directory should disappear. It only exists in the master branch, not the dev branch. However, it is still there. Why? Because the ignored program.pyc file prevents the folder from being deleted when switching branches.

The solution to this problem is to recursively delete all *.pyc files before switching branches. I can do that easily with this command.

    find . -name &quot;*.pyc&quot; -exec rm &#39;{}&#39; &#39;;&#39;

The problem is that it is annoying to have to remember to do this almost every time I change branches. I could make an alias for this command, but then I still have to remember to type it every time I change branches. I could also make an alias for git-branch, but that&#39;s no good either. The git branch command does other things besides just change branches, and I don&#39;t want to delete all pyc files every time I use it. Heck, I might even use it in a non-python repo, then what?

Is there a way to set a git hook that only executes when I change branches? Or is there some other way to set all *.pyc files to get erased whenever I switch branches?

Automatically remove *.pyc files and otherwise-empty directories when I check out a new branch

I have the following:

    array_of_hashes = [{:a=&gt;10, :b=&gt;20}, {:a=&gt;11, :b=&gt;21}, {:a=&gt;13, :b=&gt;23}]

How would I go about finding if `:a=&gt;11` exists in `array_of_hashes` 

`array_of_hashes.include?` does not seem to work

Determine if a value exists in an array of hashes

I have the following:
<pre><code class="hljs language-ruby">array_of_hashes = [{:a=>10, :b=>20}, {:a=>11, :b=>21}, {:a=>13, :b=>23}]
</code></pre>
How would I go about finding if <code>:a=>11</code> exists in <code>array_of_hashes</code>
<code>array_of_hashes.include?</code> does not seem to work

What is the right way to:

    is_array(&quot;something&quot;) # =&gt; false         (or 1)

    is_array([&quot;something&quot;, &quot;else&quot;]) # =&gt; true  (or &gt; 1)

or to get the count of items in it?

Ruby - test for array

Is there a library to convert XML to JSON in Ruby?

Ruby XML to JSON Converter?

I have an array of integers.

For example:

    array = [123,321,12389]

Is there any nice way to get the sum of them?

I know, that 

    sum = 0
    array.each { |a| sum+=a }


would work.

How to sum array of numbers in Ruby?

I know of the standard technique of having a begin &lt;some code&gt; rescue &lt;rescue code&gt; end

How does one just use the rescue block on its own.

How does it work and how does it know which code is being monitored?

How does one use rescue in Ruby without the begin and end block

What are the best practices on testing modules in RSpec? I have some modules that get included in few models and for now I simply have duplicate tests for each model (with few differences). Is there a way to DRY it up?

Testing modules in RSpec

I want to join a `String[]` with a glue string. Is there a function for this?

Java function for arrays like PHP&#39;s join()?

I need to randomly shuffle the following Array:

    int[] solutionArray = {1, 2, 3, 4, 5, 6, 6, 5, 4, 3, 2, 1};

Is there any function to do that?

Random shuffling of an array

I am looking to find the index of a given element, knowing its contents, in Java.

I tried the following example, which does not work:

    class masi { 
        public static void main( String[] args ) { 
            char[] list = {&#39;m&#39;, &#39;e&#39;, &#39;y&#39;};
         
            // should print 1
            System.out.println(list[] == &quot;e&quot;);                    
        } 
    }

Can anyone please explain what is wrong with this and what I need to do to fix it?

How to find the index of an element in an array in Java?

If I have an array like this in Bash:

    FOO=( a b c )

How do I join the elements with commas?  For example, producing `a,b,c`.

How can I join elements of an array in Bash?

Is there a function to make a copy of a PHP array to another?

I have been burned a few times trying to copy PHP arrays. I want to copy an array defined inside an object to a global outside it.

Content Type	Original Author	Original Content on Stackoverflow
Question	Christopher	View Question on Stackoverflow
Solution 1 - Ruby	Magnar	View Answer on Stackoverflow
Solution 2 - Ruby	DigitalRoss	View Answer on Stackoverflow

Determine if a value exists in an array of hashes

Ruby Problem Overview

Ruby Solutions

Solution 1 - Ruby

Solution 2 - Ruby

Automatically remove *.pyc files and otherwise-empty directories when I check out a new branch

In Objective C, can you check if an object has a particular property or message?

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